Vegetable oil-derived epoxy compositions having improved performance

ABSTRACT

Embodiments of this invention are directed to bio-based epoxy compositions, and method of their preparation and use. Other embodiments are directed to cured bio-based epoxies, and manufactured articles having bio-based epoxy coatings, adhesives, or composites.

BACKGROUND Technical Field

The present disclosure is generally directed to bio-based epoxycompositions, methods for their preparation and use, such as forcoatings, adhesives, and epoxy composites.

Description of the Related Art

Epoxy resins are widely used as matrix polymers for preparations ofcomposites, adhesives, coatings, and electrical materials because oftheir balanced mechanical performance, processability, versatility,chemical resistance, low shrinkage and other properties. Currently, over90% of commercial epoxy resins are derived from the non-renewablepetrochemical bisphenol A (BPA). However, BPA is an endocrine disruptorand thus may cause harm to human health. The increasing demand of epoxymaterials propels researchers to develop appropriate substitutes for BPAepoxy.

Use of renewable and nontoxic feedstocks for epoxies is a desirablestrategy from the perspectives of both sustainable development and humanhealth protection. In the recent decade, a variety of bio-based epoxieshave been developed using renewable lignin, rosin, plant oil, etc., asfeedstocks. Perhaps, the mostly investigated bio-epoxies are based onvegetable oils because of their abundant resources and competitive costwith respect to BPA epoxy resins. However, most of the vegetable oilepoxies, such as epoxidized soybean oil, which is built on thetriglyceride structure and bears internal epoxide groups, exhibit lowreactivity, inadequate mechanical properties, and poor heat resistance.The applications of vegetable oil-based epoxies are usually limited tothe additives or modifiers for BPA epoxy resins with relatively lowloading level (<10 wt. %). The recently developed glycidyl ester type ofbio-epoxies based on structures of fatty acid derived vegetable oils,when used for epoxy materials, show a similar curing reactivity as theBPA epoxies and exhibit much higher thermal and mechanical propertiesthan epoxidized vegetable oils (US 2018/0065915). However, for use incertain applications, fatty acid-derived bio-based epoxies alone inmatrix resins do not meet performance standards for high glasstransition temperature (T_(g)), modulus, and strength, which are met byBPA-based epoxies. In addition, adhesion of the fatty acid epoxies tosubstrates is also inferior to the adhesion properties of BPA epoxies.Therefore, there is a great need to develop compositions and methods toimprove the overall application properties of bio-based epoxies, such asfatty acid epoxies and triglyceride-based epoxies.

SUMMARY

In brief, embodiments of the present disclosure provide epoxycompositions comprising an epoxy derivable from one or more fatty acidsan aromatic non-coplanar triepoxy, and optionally a hyperbranchedprepolymer. Methods of producing a cured epoxy from such epoxycompositions, and the resulting cured epoxies are also provided.

In one embodiment, compositions comprising a fatty acid epoxy derivablefrom one or more unsaturated fatty acids and an aromatic non-coplanartriepoxy are provided.

In one embodiment, compositions comprising a fatty acid epoxy derivablefrom one or more unsaturated fatty acids; a hyperbranched prepolymerhaving terminal groups comprising epoxide groups, hydroxyl groups,carboxyl groups, or a combination thereof; and an aromatic non-coplanartriepoxy are provided.

Such compositions are useful for producing cured epoxies, and articlescomprising a cured epoxy.

In another embodiment, methods of producing a cured epoxy comprisingmixing an epoxy composition as provided herein with a curing agent toproduce a curing mixture, and polymerizing the curing mixture bymaintaining the curing mixture at a temperature and time sufficient forpolymerizing the epoxy composition, thereby producing a cured epoxy, areprovided.

In another embodiment, cured epoxies comprising a polymerized reactionproduct of an epoxy composition as described herein and one or morecuring agents are provided.

In another embodiment, articles comprising a cured epoxy as describedherein are provided. In certain embodiments, articles comprising asurface coated with a coating comprising a cured epoxy as describedherein are provided. In certain embodiments, structures comprising afirst surface and an opposing second surface joined by an adhesivebonded to the first surface and the opposing second surface, theadhesive comprising a cured epoxy as described herein. In certainembodiments, composite articles comprising fibers or particles of amatrix material embedded within the polymerization product of a curedepoxy as described herein are also provided.

These and other aspects of the disclosure will be apparent uponreference to the following detailed description.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various embodiments of thedisclosure. However, one skilled in the art will understand that thedisclosure may be practiced without these details.

Unless the context requires otherwise, throughout the presentspecification and claims, the word “comprise” and variations thereof,such as, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is, as “including, but not limited to”.

In the present description, any concentration range, percentage range,ratio range, or integer range is to be understood to include the valueof any integer within the recited range and, when appropriate, fractionsthereof (such as one tenth and one hundredth of an integer), unlessotherwise indicated. Also, any number range recited herein relating toany physical feature, such as polymer subunits, size, or thickness, areto be understood to include any integer within the recited range, unlessotherwise indicated. As used herein, the terms “about” and“approximately” mean±20%, ±10%, ±5% or ±1% of the indicated range,value, or structure, unless otherwise indicated. It should be understoodthat the terms “a” and “an” as used herein refer to “one or more” of theenumerated components. The use of the alternative (e.g., “or”) should beunderstood to mean either one, both, or any combination thereof of thealternatives.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, the appearances of thephrases “in one embodiment” or “in an embodiment” in various placesthroughout this specification are not necessarily all referring to thesame embodiment. Furthermore, the particular features, structures, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of skill in theart to which this disclosure belongs. As used in the specification andclaims, the singular form “a”, “an” and “the” include plural referencesunless the context clearly dictates otherwise.

“Alkylene” or “alkylene chain” refers to a straight or branched divalenthydrocarbon chain linking the rest of the molecule to a radical group,consisting solely of carbon and hydrogen, containing no unsaturation,and having from one to twelve carbon atoms, e.g., methylene, ethylene,propylene, n-butylene, ethenylene, propenylene, n-butenylene,propynylene, n-butynylene, and the like. The alkylene chain is attachedto the rest of the molecule through a single bond and to the radicalgroup through a single bond. The points of attachment of the alkylenechain to the rest of the molecule and to the radical group can bethrough one carbon or any two carbons within the chain. Unless statedotherwise specifically in the specification, alkylene is optionallysubstituted.

“Alkenylene” or “alkenylene chain” refers to a straight or brancheddivalent hydrocarbon chain linking the rest of the molecule to a radicalgroup, consisting solely of carbon and hydrogen, containing at least onecarbon-carbon double bond and having from two to twelve carbon atoms,e.g., ethenylene, propenylene, n-butenylene, and the like. Thealkenylene chain is attached to the rest of the molecule through asingle bond and to the radical group through a double bond or a singlebond. The points of attachment of the alkenylene chain to the rest ofthe molecule and to the radical group can be through one carbon or anytwo carbons within the chain. Unless stated otherwise specifically inthe specification, alkenylene is optionally substituted.

“Unsaturated fatty acid” refers to a fatty acid having at least onedouble bond in the carbon chain.

“Polyunsaturated fatty acid” refers to a fatty acid having at least twodouble bonds in the carbon chain.

“Epoxy” or “epoxy resin” as used herein refers to a material containingone or more compounds having polymerizable epoxide groups.

“Epoxide” refers to a cyclic ether with a three-atom ring.

“Fatty acid epoxy” refers to an epoxy that is derivable from a fattyacid. For detailed methods of deriving an epoxy from a fatty acid seeLi, R. et al., ACS Sustainable Chem. Eng. 2018, 6, 4016-4025 and US2018/0065915.

“Methoxy” refers to —OCH₃.

“Ethoxy” refers to —OCH₂CH₃.

“Non-coplanar triepoxy” refers to a compound having three epoxide groupswith at least two of the epoxide groups being non-coplanar (i.e., notlying within the same plane). In some embodiments, each of the threeepoxide groups are non-coplanar with the other two epoxide groups.

“Bio-triepoxy” refers to a triepoxy compound that is derived from aplant based source material.

“Weight average molecule weight” is a molecular weight measurement thataccounts for the weight of each molecule in a polymer composition, andcan be calculated as described in Shrivastava, A., Chapter2—Polymerization. Introduction to Plastics Engineering. William AndrewPublishing, 2018, 17-18.

“Bisphenol A based epoxy” or “BPA based epoxy” refers to an epoxycomposition with a main epoxy component (compound containing one or moreepoxide groups) that is derived from BPA. An example of a BPA basedepoxy is an epoxy composition that contains BPA diepoxy at aconcentration of 50% or more, based on the total weight of the epoxycomposition.

A “stereoisomer” refers to a compound made up of the same atoms bondedby the same bonds but having different three-dimensional structures,which are not interchangeable. The present invention contemplatesvarious stereoisomers and mixtures thereof and includes “enantiomers”,which refers to two stereoisomers whose molecules are nonsuperimposeablemirror images of one another.

The compounds of the disclosure, or their pharmaceutically acceptablesalts may contain one or more asymmetric centres and may thus give riseto enantiomers, diastereomers, and other stereoisomeric forms that maybe defined, in terms of absolute stereochemistry, as (R)- or (S)- or, as(D)- or (L)- for amino acids. In some embodiments, the present inventionis meant to include all such possible isomers, as well as their racemicand optically pure forms. Optically active (+) and (−), (R)- and (S)-,or (D)- and (L)-isomers may be prepared using chiral synthons or chiralreagents, or resolved using conventional techniques, for example,chromatography and fractional crystallisation. Conventional techniquesfor the preparation/isolation of individual enantiomers include chiralsynthesis from a suitable optically pure precursor or resolution of theracemate (or the racemate of a salt or derivative) using, for example,chiral high pressure liquid chromatography (HPLC).

The chemical naming protocol and structure diagrams used herein are amodified form of the I.U.P.A.C. nomenclature system, using the ChemDrawVersion 10 software naming program (CambridgeSoft). In chemicalstructure diagrams, all bonds are identified, except for some carbonatoms, which are assumed to be bonded to sufficient hydrogen atoms tocomplete the valency.

“Optional” or “optionally” means that the subsequently described eventof circumstances may or may not occur, and that the description includesinstances where said event or circumstance occurs and instances in whichit does not. When a functional group is described as “optionallysubstituted,” and in turn, substituents on the functional group are also“optionally substituted” and so on, for the purposes of this invention,such iterations are limited to five, preferably such iterations arelimited to two.

Compounds for Use in the Epoxy Compositions Fatty Acid-Derived Epoxy

As noted in the Summary of the Invention, epoxy compositions of thepresent disclosure include a fatty acid epoxy. In embodiments, the fattyacid epoxy is derived from one or more unsaturated fatty acids. Inparticular embodiments, the fatty acid epoxy is derived from one or morepolyunsaturated fatty acids. In particular embodiments, the one or moreunsaturated fatty acids are selected from linoleic acid, linolenic acid,and eleostearic acid.

In some embodiments, the fatty acid epoxy comprises one or morecompounds having a structure of Formula (IV):

wherein R¹ and R² are each independently straight alkylene chain or astraight alkenylene chain, selected such that together R¹ and R² containa total of 12 carbons.

In certain embodiments, the one or more compounds having the structureof Formula (I) are selected from:

In certain embodiments, the fatty acid epoxy is a compound selectedfrom:

In some embodiments, the fatty acid epoxy is derived from a fatty acidcomponent of a hydrolysis product of vegetable oil. The vegetable oilmay be flax seed oil, linseed oil, hempseed oil, or tungsten oil.Vegetable oils contain triglycerides that upon hydrolysis produce afatty acid component and a glycerol component. In certain embodiments,the fatty acid component of the hydrolysis product comprises about 65%to about 80% polyunsaturated fatty acids, based on total weight of thefatty acid component of the hydrolysis product.

In certain embodiments, the vegetable oil comprises triglycerides havinga fatty acid content including linoleic acid (C18:2) and one or more oflinolenic acid (C18:3) or eleosteric acid (C18:3).

In particular embodiments, the vegetable oil comprises a triglyceridehaving a structure of Formula (III):

For preparation of the fatty acid epoxies described herein, detailedmethods can be found for example in Li, R. et al., ACS Sustainable Chem.Eng. 2018, 6, 4016-4025 and US 2018/0065915.

Hyperbranched Prepolymer

As noted in the Summary of the Invention, epoxy compositions of thepresent disclosure optionally include a hyperbranched prepolymer.

In some embodiments, the hyperbranched prepolymer has terminal groupscomprising epoxide groups, hydroxyl groups, carboxyl groups, or acombination thereof. In certain embodiments, the hyperbranchedprepolymer has terminal groups consisting of: epoxide groups andhydroxyl groups; epoxide groups and carboxyl groups; or epoxide groups,hydroxyl groups, and carboxyl groups.

In certain embodiments, the hyperbranched prepolymer has a weightaverage molecule weight within the range of about 1,000 g/mol to about10,000 g/mol. In particular embodiments, the hyperbranched prepolymerhas a weight average molecule weight within the range of about 1,000g/mol to about 3,000 g/mol. In particular embodiments, the hyperbranchedprepolymer has a weight average molecule weight within the range ofabout 8,000 g/mol to about 3,000 g/mol.

In certain embodiments, the hyperbranched prepolymer comprises a polymerobtained by polymerizing (i) monomer A having polymerizable epoxy groupsor carboxyl groups and (ii) monomer B having three polymerizablehydroxyl groups.

In certain embodiments, monomer A is bisphenol A (BPA) diepoxy, ethyleneglycol diepoxy (EGDGE), polyethylene glycol diepoxy (PEGDGE),maleopimaric acid (MPA), or a combination thereof.

In particular embodiments, monomer A is BPA diepoxy. BPA diepoxy is areaction product of epichlorohydrin and bisphenol A, is commerciallyavailable (e.g., DER™ 331, DOW CHEMICAL CO.), and has the followingstructure:

In particular embodiments, monomer A is ethylene glycol or PEG diepoxy.Ethylene glycol diepoxy is commercially available from POLYSCIENCES INCand has the following structure:

wherein n1 is 2. PEG diepoxy (PEG diglycidyl ether or PEGDGE) iscommercially available from SIGMA-ALDRICH and POLYSCIENCES INC (PEGDGE200, PEGDGE 400, PEGDGE 600, and PEGDGE 100) and comprises the followingstructure:

wherein n1 is greater than 2 and up to 12. In particular embodiments,monomer A comprises the following structure:

wherein n1 is 2 to 12.

In particular embodiments, monomer A is MPA. MPA can be synthesized asdescribed in Gonis, G. et al. Eng. Chem. Prod. Res. Dev. 1973, 12, 4,326-327 and has the following structure;

In certain embodiments, monomer B is2-ethyl-2-hydroxymethyl-1,3-propanediol (TMP);2-hydroxymethyl-2-methyl-1,3-propanediol;2-hydroxymethyl-1,3-propanediol; 4,4′,4″-trihydroxyltriphenylmethane(THTPM); or a combination thereof.

In particular embodiments, monomer B is TMP. TMP has the followingstructure:

In particular embodiments, monomer B is2-hydroxymethyl-2-methyl-1,3-propanediol, which has the followingstructure:

In particular embodiments, monomer B is 2-hydroxymethyl-1,3-propanediol(trimethylolmethane or tris(hydroxymethyl)methane), which has thefollowing structure:

In particular embodiments, monomer B is4,4′,4″-trihydroxyltriphenylmethane (THTPM). THTPM may be synthesized asdescribed in Luo, L., et al. J. APPL. POLYM. SCI. 2013, DOI:10.1002/APP.39257, and has the following structure:

In certain embodiments, the hyperbranched prepolymer comprises acompound having one of the following structures:

wherein:

X at each occurrence is independently selected from:

andW at each occurrence is selected from:

wherein

indicates a continued branch of the hyperbranched prepolymer and whereinn1=2 to 12.

In some embodiments, the prepolymer monomers of the hyperbranchedprepolymer further comprise monomer C, having two polymerizable carboxylgroups.

In certain embodiments, the monomer C is selected from:

wherein n2 is 2 to 12.

In certain embodiments, the hyperbranched prepolymer comprises acompound having the structure of Formula (VI):

wherein:

X at each occurrence is independently selected from

W at each occurrence is independently selected from

and

Z is selected from

wherein n1 is 2 to 12, n2 is 2 to 12, and

indicates a continued branch of the hyperbranched prepolymer.

For preparation of the hyperbranched prepolymers described herein,detailed methods may be found, for example, in Han J. et al.,Macromolecules. 2018, 51, 7689-6799, and Luo L. et al., J. Appl. Polym.Sci. 2013, DOI: 10.1002/APP.39257.

Non-Coplanar Triepoxy

As noted in the Summary epoxy compositions of the present disclosureinclude an aromatic non-coplanar triepoxy. In some embodiments, thearomatic non-coplanar triepoxy is a non-coplanar bio-triepoxy, whichrefers to a non-coplanar triepoxy that is derived from a plant source.In particular embodiments, the non-coplanar bio-triepoxy is a reactionproduct of vanillin and guiacol.

In certain embodiments, the non-coplanar triepoxy is a compound havingthe structure of Formula (VII):

wherein R¹ and R² at each occurrence are independently H, —OCH₃, or—OCH₂CH₃.

In some embodiments, the compound having the structure of Formula (VII)has the following structure:

For preparation of aromatic non-coplanar triepoxies described herein,detailed methods may be found, for example, in Liu T. et al.Macromolecules. 2018, 51, 5577-5585; Zhao S. et al. ACS SustainableChem. Eng. 2018, 6, 7600-7608; and Hernandez E. D. et al. ACSSustainable Chem. Eng. 2016, 4 (8), 4328.

Epoxy Compositions

Provided herein are epoxy compositions comprising a fatty acid epoxy, anaromatic non-coplanar triepoxy, and optionally a hyperbranchedprepolymer. The epoxy compositions have surprisingly strong performanceproperties, such as improved Tg, improved mechanical strength, andimproved adhesion properties without compromising other properties. Thestrong performance of the epoxy composition makes possible the use ofthe fatty acid epoxy as a main matrix component with high loading levels(e.g., up to 80 wt. %). Surprisingly, the prepared epoxy compositionsexhibit comparable performance to materials prepared from a commercialBPA epoxy resin.

In some embodiments, the fatty acid epoxy is present in the epoxycomposition at a concentration within a range of up to about 80 wt. %.In some embodiments, the fatty acid epoxy is present at a concentrationwithin a range of about 40 wt. % to about 80 wt. %. In some embodiments,the fatty acid epoxy is present at a concentration within a range ofabout 30 wt. % to about 50 wt. %. In certain embodiments, the fatty acidepoxy is present at a concentration of about 40 wt. %, about 45 wt. %,about 50 wt. %, about 55 wt. %, about 60 wt. %, about 65 wt. %, about 70wt. %, about 75 wt. %, or about 80 wt. %.

In some embodiments, the hyperbranched prepolymer is present in theepoxy composition at a concentration of about 50 wt. % or less. Incertain embodiments, the hyperbranched prepolymer is present at aconcentration within a range of about 5 wt. % to about 50 wt. %. Incertain embodiments, the hyperbranched prepolymer is present at aconcentration of about 5 wt. %, about 10 wt. %, about 15 wt. %, about 20wt. %, about 25 wt. %, about 30 wt. %, about 35 wt. %, about 40 wt. %,about 45 wt. %, or about 50 wt. %.

In some embodiments, the aromatic non-coplanar triepoxy is present at aconcentration of about 50 wt. % or less. In certain embodiments, thearomatic non-coplanar triepoxy is present at a concentration within arange of about 5 wt. % to about 50 wt. %. In some embodiments, thearomatic non-coplanar triepoxy is present at a concentration within arange of about 40 wt. % to about 70 wt. %. In certain embodiments, thearomatic non-coplanar triepoxy is present at a concentration of about 5wt. %, about 10 wt. %, about 15 wt. %, about 20 wt. %, about 25 wt. %,about 30 wt. %, about 35 wt. %, about 40 wt. %, about 45 wt. %, or about50 wt. %.

In particular embodiments, the epoxy compositions include the fatty acidepoxy at a concentration of about 60 wt. %, the hyperbranched prepolymerat a concentration of about 20 wt. %, and the aromatic non-coplanartriepoxy at a concentration of about 20 wt. %. Such epoxy compositionsmay be useful, for example, for producing an anhydride (e.g., nadicmethyl anhydride) cured epoxy.

In particular embodiments, the epoxy compositions include the fatty acidepoxy at a concentration of about 40 wt. %, the hyperbranched prepolymerat a concentration of about 40 wt. %, and the aromatic non-coplanartriepoxy at a concentration of about 20 wt. %. Such epoxy compositionsmay be useful, for example, for producing an amine (e.g.,diethylenetriamine) cured epoxy.

In particular embodiments, the epoxy compositions include the fatty acidepoxy at a concentration of about 65 wt. %, the hyperbranched prepolymerat a concentration of about 10 wt. %, and the aromatic non-coplanartriepoxy at a concentration of about 25 wt. %. Such epoxy compositionsmay be useful, for example, for producing epoxy coating.

In particular embodiments, the epoxy compositions include the fatty acidepoxy at a concentration of about 60 wt. %, the hyperbranched prepolymerat a concentration of about 10 wt. %, and the aromatic non-coplanartriepoxy at a concentration of about 30 wt. %. Such epoxy compositionsmay be useful, for example, for producing an epoxy composite.

In particular embodiments, the epoxy compositions include the fatty acidepoxy at a concentration of about 40 wt. % and the aromatic non-coplanartriepoxy at a concentration of about 60 wt. %. In particular embodimentsthe epoxy composition does not include a hyperbranched prepolymer. Inparticular embodiments the epoxy composition does not include acomponent that is derived from BPA.

Methods of Use

In some aspects, provided herein are methods of producing a cured epoxy.In embodiments, the method comprises mixing an epoxy composition asdescribed herein with a curing agent to produce a curing mixture, andpolymerizing the curing mixture. Polymerizing the curing mixture may beachieved by maintaining the curing mixture at a temperature and timeperiod sufficient for polymerizing the epoxy composition, therebyproducing a cured epoxy.

In some embodiments, the curing agent is an anhydride-based curing agentor an amine-based curing agent. In particular embodiments, the curingagent is an anhydride-based curing agent. Anhydride-based curing agentsinclude phthalic anhydride, pyromellitic dianhydride, chlorendicanhydride, and nadic methyl anhydride (NMA). In particular embodiments,the curing agent is an amine-based curing agent. Examples of amine-basedcuring agents include triethylenetetramine (TTA), tetraethylenepentamine(TEPA), diethylaminopropylamine (DEAPA), and diethylenetriamine (DETA).

In particular embodiments, the curing agent is an anhydride-based curingagent. In some embodiments, the curing mixture comprises ananhydride-based curing agent at a concentration within a range of about70 wt. % to about 90 wt. %. In particular embodiments, the curingmixture comprises an anhydride-based curing agent at a concentration ofabout 80 wt. %.

In particular embodiments, the curing agent is an amine-based curingagent. In some embodiments, the curing mixture comprises an amine-basedcuring agent at a concentration within a range of about 5 wt. % to about25 wt. %. In particular embodiments, the curing mixture comprises ananhydride-based curing agent at a concentration of about 15 wt. %.

In some embodiments, the temperature that is sufficient for polymerizingthe epoxy composition is at least 20° C.

In particular embodiments, the temperature is 75° C. or greater. Attemperatures of 75° C. or greater the polymerizing may be achieved bymaintaining the curing mixture at the temperature for as few as fifteenminutes, thirty minutes, one hour, or two hours. In particularembodiments, the temperature is about 25° C. In particular embodiments,the temperature is 75° C. or greater and the time period is at leastabout 30 minutes.

At a temperature of about 25° C. polymerizing may be achieved bymaintaining the curing mixture at the temperature for a time period ofat least about 6 hours, at least about 8 hours, at least about 10 hours,at least about 12 hours, at least about 18 hours, at least about 24 day,or at least about 2 days. In particular embodiments, the temperature isabout 25° C. and the time period is at least about 24 hours.

In some embodiments, one or more additional components are added to thecuring mixture. Examples of additional components that may be addedinclude accelerators, hardeners, pigments, and fillers.

In particular embodiments, the curing mixture further comprises anaccelerator. Accelerators may be added to accelerate the curingreaction. Examples of accelerators include tertiary amines, carboxylicacids and alcohols (especially phenols). In particular embodiments, anaccelerator is added to the curing mixture at a concentration of about0.1 wt. % to about 1 wt. %. In particular embodiments, the acceleratorcomprises diethyl methyl imidazole.

In some aspects, the methods described herein may be useful forproducing, for example, epoxy adhesives, epoxy coatings, and epoxycomposites.

In particular embodiments, the polymerizing is performed with the curingmixture impregnated into a matrix material, to produce an epoxycomposite. In particular embodiments, the matrix material comprisesglass fibers, carbon fibers, inorganic filler particles, or combinationsthereof. Examples of glass fibers include fiberglass, E glass fiber, Sglass fiber, and C glass fiber. Examples of inorganic filler particlesinclude nano clay, silicon dioxide, calcium oxide, boron fiber, quartz,aluminium oxide, and silicon carbide or disilicon carbide containingtitanium fiber. Examples of carbon fibers include graphite fiber, carbonnanotubes, and nano composite fibers. Other matrix materials includepoly paraphenylene terephthalamide, poly(p-phenylene benzobisoxazole)fiber, ultrahigh molecular weight polyethylene fibers, high and lowdensity polyethylene fibers, polypropylene fibers, nylon fibers, andbiodegradable natural fibers such as cellulose fibers.

In particular embodiments, the polymerizing is performed within a mold.For example, the curing mix may be prepared and then poured into themold prior to the polymerizing. The cured epoxy obtained afterpolymerizing replicate the shape of the mold. The mold may be made of,for example, metal, silicon, or plastic.

In particular embodiments, the polymerizing is performed on at least aportion of a surface of an article, resulting in an epoxy coating on thearticle. Epoxy coatings may be used on a variety of surfaces, such aswood, metal, glass, stone, cement, ceramic (e.g., tile), thermoplasticssuch as polyethylene or vinyl, thermosets such as polyeurethane, and anymaterial used as a flooring. In particular embodiments, the surface ofthe article comprises wood, metal, glass, stone, cement, ceramic, athermoplastic, or a thermoset.

In particular embodiments, the the polymerizing is performed between aportion of a surface of a first article and a portion of a surface of asecond article, resulting in adhesion of the first article to the secondarticle. Epoxy adhesives may be used to adhere a variety of surfaces,such as wood, metal, glass, stone, cement, thermoplastics such aspolyethylene or vinyl, and thermosets. In particular embodiments, thesurface of the first article or the surface of the second articlecomprises wood, metal, glass, stone, cement, ceramic, a thermoplastic,or a thermoset.

Cured Epoxies

In some aspects, provided herein are cured epoxies comprising apolymerized reaction product of an epoxy composition as described hereinand one or more curing agents. The curing agent may be, for example, ananhydride-based curing agent or an amine-based curing agent such asthose previously described.

In certain aspects, provided herein are articles comprising a curedepoxy. In some embodiments, the articles comprising the cured epoxy haveperformance properties that are equivalent to those of an articlecomprising a BPA based cured epoxy. Performance properties may include,for example, glass transition temperature, viscosity, tensile strength,impact strength, peel strength, modulus, pencil hardness, adhesion, andsolvent resistance. Methods for measuring such performance propertiesare known by those of skill in the art and are published by the AmericanSociety for Testing Materials (ASTM). For pencil hardness, the curedepoxy may be considered to have equivalent or better hardness than a BPAbased epoxy if the pencil hardness grade is the same or is graded asharder. For strength based performance properties (e.g., tensilestrength, impact strength, and peel strength), a cured epoxy may beconsidered to have equivalent or better adhesion than a BPA based epoxyif the strength value is within ±20% (or greater) than the strengthvalue measured for the BPA based epoxy. For glass transitiontemperature, Tg, a cured epoxy may be considered to have an equivalentor better performance than a BPA based epoxy if the Tg is within ±20° C.of the Tg for a cured BPA based epoxy.

In particular embodiments, the cured epoxy comprises a glass transitiontemperature, Tg, of at least about 40° C., at least about 45° C., atleast about 50° C., or at least about 55° C. In particular embodiments,the cured epoxy comprises a glass transition temperature within a rangeof about 50° C. to about 70° C. In particular embodiments, the curedepoxy comprises a peel strength of at least about 6 N/mm, at least about7 N/mm, or at least about 8 N/mm.

In certain aspects, provided herein are articles comprising a surfacecoated with a coating comprising a cured epoxy. In particularembodiments, the coating comprises a primer. In particular embodiments,the epoxy coating has a layer thickness within a range of about 100 μmand about 10 mm. In particular embodiments, the coating has a layerthickness of about 50 μm, about 100 μm, about 150 μm, about 200 μm, orabout 250 μm. In certain embodiments, the epoxy coating has glasstransition temperature of at least about 40° C. or at least about 45° C.In particular embodiments, the epoxy coating has a pencil hardness of 5Bor harder (see ASTM D3363). In particular embodiments, the epoxy coatinghas a pencil hardness that is at least as hard as a BPA based epoxycoating cured using the same curing agent.

In certain aspects, provided herein are structures comprising a firstsurface and an opposing second surface joined by an adhesive bonded tothe first surface and the opposing second surface, the adhesivecomprising a cured epoxy. Epoxy adhesives may be useful, for example,for construction of aircraft, automobiles, bicycles, boats, golf clubs,skis, snowboards, and other applications where high strength bonding isrequired. In particular embodiments, the adhesive has one or moreperformance properties that are equivalent to or better than a BPA basedepoxy adhesive. A cured epoxy may be considered to have equivalent orbetter adhesion than a BPA based epoxy if the adhesion grade is the sameor a higher level of adhesion than the BPA based epoxy as measured by astandard tape test (see ASTM D3359).

In certain aspects, provided herein are composite articles comprisingfibers or particles of a matrix material and a cured epoxy as describedherein, wherein the fibers or particles of the matrix material areembedded within the polymerized product of the cured epoxy. Inparticular embodiments, the composite article comprises a glass fibercomposite article, a carbon fiber composite article, a magneticcomposite article (see Gu, H. et al., ACS Appl. Mater. Interfaces 2012,4, 10, 5613-5624), a flame-retardant composite article (see Jiang, J. etal. J. Mater. Chem. A, 2015, 3, 4284-4290), or a combination thereof.

The following Examples may be used by one skilled in the art todemonstrate the improved properties of the epoxy compositions of theinvention.

EXAMPLES Example 1 Preparation of Anhydride Cured Hempseed Oil FattyAcid-Derived Epoxy Containing Bio-Triepoxy and Hyperbranched Prepolymer

For production of an anhydride cured epoxy, 60 parts by weight ofhempseed oil fatty acid epoxy (FA-EP) prepared as described in Li, R. etal., ACS Sustainable Chem. Eng. 2018, 6, 4016-4025 and US20180065915A1,20 parts of an aromatic non-coplanar triepoxy of Formula (VIIA) and 20parts of a hyperbranched prepolymer (HBP) of Formula IV were mixed undermagnetic stirring at room temperature. After a homogeneous mixture wasobtained, 80 parts of nadic methyl anhydride (NMA) as curing agent wasadded at room temperature. Finally, diethyl methyl imidazole, theaccelerator, was added. After a homogeneous mixture was formed, it wasdegassed and cured in a metal mold. The curing was a three-step process:100° C. for 2 hours, 150° C. for 3 hours, and 180° C. for 2 hours. Aftercuring, the sample was allowed to cool down naturally to roomtemperature. The cured product exhibited similar properties as the NMAcured BPA epoxy system.

TABLE 1 Viscosity^(a) Tg Tensile strength Impact strength (Pa · s) (°C.) (mpa) (kj/m²) Resin from Example 1.6 105.5 65.1 23.8 1 NMA cured BPA2.7 135.1 68.5 15.6 epoxy ^(A)Viscosity of resin before curing, and thetest was performed at 25° C.

Example 2 Preparation of Amine Cured Bio-Based Epoxy Composition

Under magnetic stirring, 40 parts by weight of the hempseed oil fattyacid-derived epoxy (FA-EP), 20 parts of the bio-triepoxy and 40 parts ofhyperbranched prepolymer (HBP) were mixed at room temperature. TheFA-EP, the bio-triepoxy, and the HBP were the same as those used inExample 1. After a homogeneous mixture was obtained, 15 parts ofdiethylenetriamine (DETA) as curing agent was added under continuousstirring at room temperature. After a homogeneous mixture was formed, itwas degassed and cured in a metal mold. The curing was a one-stepprocess: 95° C. for 30 min After curing, the sample was allowed to cooldown naturally to room temperature. As shown in Table 2, the curedproduct exhibited similar properties as the commercial ENTROPY RESINS®(GOUGEON BROTHERS, INC., Bay City, Mich.) epoxy resin system, which isan epoxy system with BPA epoxy as a main component and has a bio-basedcomponent that is approximately 30% of the composition.

TABLE 2 Viscosity^(a) Tg Peel strength^(b) Modulus (Pa · s) (° C.)(N/mm) (MPa) Resin from 4.9 52.7° C. 9.0 1990 Example 2 Commercial 3.759.9° C. 10.4 2060 Entropy Epoxy Resin ^(a)Viscosity of resin beforecuring. Test performed at 25° C. ^(b)Peel strength of adhesively bondedresin and polyethylene.

Additionally, DETA epoxies with varied ratios of the fatty acid epoxy,the hyperbranched polymer (HBP) and the aromatic non-coplanar triepoxywere evaluated. Results are shown in Table 3.

TABLE 3 FA-EP Bio-triepoxy HBP Peel strength ^(b) T_(g) Resin^(a) (part)(part) (part) (N/mm) (° C.) Resin 0 100 0 0 2.1 23.6 Resin 1 40 20 409.0 57.2 Resin 2 40 40 20 7.6 64.8 Resin 3 40 60 0 5.3 73.6 ^(a)Theresin was cured with 15 parts DETA at 90° C. for 30 min; ^(b) peelstrength of adhesively bonded resin and polyethylene.

Example 3 Preparation of a Bio-Based Epoxy Coating

Under magnetic stirring, 65 parts by weight of hempseed oil fattyacid-derived epoxy (FA-EP), 25 parts of bio-triepoxy and 10 parts ofhyperbranched prepolymer (HBP) were mixed at room temperature. TheFA-EP, the bio-triepoxy, and the HBP were the same as those used inExample 1. After a homogeneous mixture was obtained, 15 parts ofdiethylenetriamine (DETA) as curing agent was added under continuousstirring at room temperature. After a homogeneous mixture was formed, itwas degassed and coated onto a tin plate with a layer thickness of ˜100μm. The curing was performed at room temperature (25° C.) for 3 days.The prepared coating exhibited similar properties as the DETA cured BPAepoxy resin system (Table 4).

TABLE 4 Solvent Viscosity^(a) T_(g) Pencil resistance (Pa · s) (° C.)hardness^(b) Adhesion^(c) (rub test) Resin from 0.8 48.6 5 H 5 B >400example 3 DETA cured 5.3 49.7 5 H 5 B >400 BPA epoxy ^(a)Viscosity ofresin before curing, and the test was performed at 25° C.; ^(b)thehardness of the coating was monitored by pencil test according to ASTMD3363; ^(c)the adhesion property of the coating was measured by tapetest, according to ASTM D3359-17; ^(d)the solvent resistance of thecoating was determined using solvent rubs according to ASTM D5402-15.

Example 4 Glass Fiber Reinforced Bio-Based Epoxy Composites by ManualImpregnation

A glass fiber sheet of 250×250 mm was placed on a Teflon film. This wasthen manually impregnated with resin (a mixture composed of FA-EP (60parts), bio-triepoxy (30 parts), HBP (10 parts) and DETA (15 parts))using a brush. The FA-EP, the bio-triepoxy, and the HBP were the same asthose used in Example 1. Subsequently, another glass fiber sheet of250×250 mm was placed on top of it and the same operation was repeateduntil a total of 8 impregnated layers were completed. The system wassealed with a vacuum bag. The enclosed part was then compacted byapplying vacuum. Once air was evacuated, curing was carried out in anoven at 95° C. for 30 min. After curing, the sample was allowed to cooldown naturally to room temperature.

All of the U.S. patents, U.S. patent application publications, U.S.patent applications, foreign patents, foreign patent applications andnon-patent publications referred to in this specification areincorporated herein by reference in their entireties.

Although the foregoing invention has been described in some detail tofacilitate understanding, it will be apparent that certain changes andmodifications may be practiced within the scope of the appended claims.Accordingly, the described embodiments are to be considered asillustrative and not restrictive, and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalents of the appended claims.

1. An epoxy composition comprising: a fatty acid epoxy derivable fromone or more unsaturated fatty acids; a hyperbranched prepolymer havingterminal groups comprising epoxide groups, hydroxyl groups, carboxylgroups, or a combination thereof; and an aromatic non-coplanar triepoxy.2-4. (canceled)
 5. The epoxy composition of claim 1, wherein the fattyacid epoxy is a compound having a structure of Formula (I):

wherein R¹ and R² are each independently a straight alkylene chain or astraight alkenylene chain, selected such that together R¹ and R² containa total of 12 carbons.
 6. (canceled)
 7. The epoxy composition of claim1, wherein the fatty acid epoxy is a compound selected from:

8-9. (canceled)
 10. The epoxy composition of claim 1, wherein the fattyacid epoxy is a fatty acid epoxy derivable from a fatty acid componentof a hydrolysis product of vegetable oil that comprises a triglyceridehaving a structure of Formula (III):

11-13. (canceled)
 14. The epoxy composition of claim 1, wherein thehyperbranched prepolymer has terminal groups consisting of: epoxidegroups and hydroxyl groups; epoxide groups and carboxyl groups; orepoxide groups, hydroxyl groups, and carboxyl groups. 15-18. (canceled)19. The epoxy composition of claim 1, wherein the hyperbranchedprepolymer comprises a compound having one of the following structures:

wherein: X is:

or a combination thereof; and W is:

or a combination thereof, wherein

indicates a continued branch of the hyperbranched prepolymer and whereinn1=2 to
 12. 20-21. (canceled)
 22. The epoxy composition of claim 1,wherein the hyperbranched prepolymer comprises a compound having thestructure of Formula (VI):

wherein: X at each occurrence is independently selected from

W at each occurrence is independently selected from

and Z is selected from

wherein n1 is 2 to 12, n2 is 2 to 12, and

indicates a continued branch of the hyperbranched prepolymer.
 23. Theepoxy composition of claim 1, wherein the aromatic non-coplanar triepoxyis a compound having the structure of Formula (VII):

wherein R¹ and R² at each occurrence are independently H, —OCH₃, or—OCH₂CH₃.
 24. The epoxy composition of claim 23, wherein the compoundhaving the structure of Formula (VII) has the following structure:


25. The epoxy composition of claim 1, wherein the fatty acid epoxy ispresent at a concentration of about 60% wt. %, the hyperbranchedprepolymer is present at a concentration of about 20 wt. %, and thearomatic non-coplanar triepoxy is present at a concentration of about 20wt. %, based on total weight of the epoxy composition. 26-27. (canceled)28. An epoxy composition comprising a fatty acid epoxy derivable fromone or more unsaturated fatty acids and an aromatic non-coplanartriepoxy. 29-30. (canceled)
 31. The epoxy composition of claim 28,wherein the fatty acid epoxy is a compound having a structure of Formula(I):

wherein R¹ and R² are each independently linear alkylene or linearalkenylene, selected such that together R1 and R2 contain a total of 12carbons.
 32. (canceled)
 33. The epoxy composition of claim 28, whereinthe fatty acid epoxy is a compound selected from:

34-35. (canceled)
 36. The epoxy composition of claim 28, wherein thefatty acid epoxy is a fatty acid epoxy derivable from a fatty acidcomponent of a hydrolysis product of vegetable oil comprising atriglyceride having a structure of Formula (III):

37-39. (canceled)
 40. The epoxy composition of claim 28, wherein thearomatic non-coplanar triepoxy is a compound having the structure ofFormula (VII):

wherein R¹ and R² at each occurrence are independently H, —OCH₃, or—OCH₂CH₃.
 41. The epoxy composition of claim 40, wherein the compoundhaving the structure of Formula (VII) has the following structure:


42. (canceled)
 43. A method of producing a cured epoxy, the methodcomprising mixing an epoxy composition comprising: a fatty acid epoxyderivable from one or more unsaturated fatty acids; a hyperbranchedprepolymer having terminal groups comprising epoxide groups, hydroxylgroups, carboxyl groups, or a combination thereof; and an aromaticnon-coplanar triepoxy, with a curing agent to produce a curing mixture,and polymerizing the curing mixture by maintaining the curing mixture ata temperature and time sufficient for polymerizing the epoxycomposition, thereby producing a cured epoxy.
 44. The method of claim43, wherein the curing agent comprises an anhydride curing agent or anamine curing agent. 45-51. (canceled)
 52. The method of claim 43,wherein the curing mixture further comprises an accelerator added to thecuring mixture at a concentration of about 0.1 wt. % to about 1 wt. %,based on total weight of the curing mixture. 53-59. (canceled)
 60. Themethod of claim 43, wherein the polymerizing is performed between aportion of a surface of a first article and a portion of a surface of asecond article, resulting in adhesion of the first article to the secondarticle. 61-66. (canceled)